Question

The length and breadth of a rectangular field are in the ratio $4:3$. Its area is 6,912 $m^2$ .Find the cost of fencing the field at Rs.2.50 per metre

Answer 1

let length,breadth,area be $l,b,A$ respectively.

$A=6912m^2$

$l:b=4:3$

$b=\frac{3\times l}{4}$

$A=l\times b$

$A=l\times \frac{3l}{4}$

$A=\frac{3l^2}{4}$

$\frac{3l^2}{4}=6912$

$l^2=\frac{4\times 6912}{3}$

$l^2=9216$

$l=96m$

$b=\frac{3\times 96}{4}=72m$

the cost of fencing depends on the perimeter of rectangular field

perimeter$=2\times (l+b)=2\times (96+72)=336m$

cost per meter in Rs $=2.50$

cost for total fencing $=2.50\times 336=Rs.840$